This invention relates to devices for the initiation of chemical reactions. Initiators are devices that initiate a chemical reaction, and in many cases an initiator will initiate an energetic output which then can be used to drive another chemical reaction such as a pyrotechnic, propellant or detonation output. Initiators or detonators induce hot spots within the energetic material. These hot spots induce deflagration, ultimately leading to detonation. Hot spots can be induced in a number of ways, including heat, friction and compression.
Applications which require precise timing typically use electrical initiators rather than mechanical initiators. The three common types of electrical initiators are hot wire, exploding bridgewire (EBW) and slapper. The slapper detonator has distinct advantages in terms of efficiency, safety and reliability after aging. A shock is delivered to the explosive energetic material through a high impact flyer (or ‘slapper’). The impact is high enough to detonate the explosive. The slapper is commonly constructed of thin plastic or metal and is driven by a plasma created by passing a large amount of current through a thin metal wire or strip.
Some advantages of a slapper detonator are 1) the energy required to fire is low; 2) insensitive explosives can be initiated directly; 3) a larger area of the explosive is impacted and thus slappers are more efficient than EBWs; 4) the foil is not in direct contact with the explosive before firing, thus reducing the potential for undesirable chemical interactions. The basic design elements of a slapper detonator are 1) lead wires, 2) header, 3) exploding foil or wire, 4) flyer plate, 5) barrel assembly, 6) high-density explosive, and 7) cup.